This surfaced because I moved global shortcut handling before menu dispatch recently, and global keyboard handling didn't look at the opt button, so it thought cmd-opt-left meant cmd-left and swallowed the event.

BUG=25396
TEST=Focus text box in web. cmd-opt-left/right should switch tabs, cmd-left/right should move cursor in text box. Focus web background. cmd-opt-left/right should switch tabs, cmd-left/right should do history navigation. Focus omnibox. cmd-opt-left/right should still switch tabs, cmd-left/right should move cursor. cmd-1/2 should switch tabs in all three places, cmd-opt-1/2 should not do anything.

Review URL: http://codereview.chromium.org/313004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@29646 0039d316-1c4b-4281-b951-d872f2087c98